Method for Processing Video Data for a Display Device

1. Method for processing RGB video picture data having a video (signal) level for display on a display device having a plurality of luminous elements corresponding to the colour components of pixels of a video picture, wherein a dithering method is applied to the video data to refine a grey-scale portrayal for displaying the video pictures, wherein, within the dithering method the input video data is converted to higher bit resolution and dithering numbers are added to the input video data in higher bit resolution, followed by a step with which the input video data is converted to final bit resolution, the dithering method including at least one of: (a) the dithering is made cell-based such that to each colour component R, G, B of a given pixel, and dependent on the identity of the colour component, a different dithering number from a dither pattern is added to each colour component of a given pixel, wherein the dither pattern comprises different dithering numbers from a set of dithering numbers; (b) the bit resolution of the dithering numbers is made dependent on a region/object in the video picture; and (c) the bit resolution of the dithering numbers is made dependent on the video (signal) level.

2. Method according to claim 1 , wherein for the cell-based dithering the video picture is divided into a number of sections and a static 3-dimensional dithering pattern is defined which is used repeatedly in a video sequence, wherein a first dimension corresponds to a video line number, a second dimension corresponds to a number of cells within a video line section and a third dimension corresponds to a number of video frames.

3. Method according to claim 2 , wherein the static 3-dimensional dithering pattern is defined for a section of 4 lines with 4 cells each for a number of 4 consecutive frames with a bit-resolution for the dithering numbers of 3 bits.

4. Method according to claim 1 , wherein for the region/object-based dithering, the information about different video objects/region is taken over from an MPEG4 data stream.

5. Method according to claim 1 , wherein to each of the specific sets of dithering numbers for the dithering process, a corresponding masking bit pattern is assigned which determines by Boolean operation which of the bits of a high resolution dithering number are to be taken for the resulting final dithering number.

6. Method according to claim 1 , wherein for the video level-based dithering, a full range of the video (signal) level is subdivided in a number of sections and to each section a corresponding masking bit pattern is assigned which determines by Boolean operation which of the bits of a high resolution dithering number are to be taken for the resulting final dithering number.

7. Method according to claim 6 , wherein the full video level range from 0 to 255 is subdivided in 4 sections, in particular 0 to 31, 32 to 63, 64 to 127, and 128 to 255 and correspondingly the following bit resolutions are used for the ranges, 3-bit, 2-bit, 1-bit, 0-bit and wherein the bit resolution decreases as the video level range increases.

9. Method according to claim 1 , wherein the method is used for the video signal processing in a Plasma display device.

10. Apparatus for processing video pictures having a grey-scale portrayal for display on a display device having a plurality of luminous elements corresponding to the RGB colour components of pixels of a video picture, said apparatus comprising a dithering unit which calculates dithering numbers that are added to video picture data having a video (signal) level to refine the grey-scale portrayal in the video pictures, wherein, within the dithering unit conversion means that convert the input video data to higher bit resolution are comprised addition means that add dithering numbers to the input video data in higher bit resolution, and processing means performing a step with which the input video data is converted to final bit resolution, the dithering unit calculating dithering numbers according to at least one of: (a) applying different dithering numbers for the RGB colour components so that, dependent on the identity of the colour component, a different dithering number from a dither pattern is added to each of the RGB components of a given pixel; wherein the dither pattern comprises different dithering numbers from a set of dithering numbers; (b) selecting the bit resolution of dithering numbers dependent on the region/object in the video picture; and (c) selecting the bit resolution of the dithering numbers dependent on the video (signal) level.